行星际激波导致内磁层脉冲电场的模拟研究

Simulation study on the Impulsive Electric Field induced by an interplanetary shock

行星际激波压缩地球磁层会产生全球尺度的脉冲电场,这种脉冲电场进而会导致相对论电子发生快速的加速和注入行为,因此脉冲电场的研究对内磁层的动力学问题的理解具有重要的意义.我们利用SWMF模型模拟了2015年12月19日的行星际激波事件,来研究内磁层脉冲电场的演化和分布特性,模拟结果表明:(1)脉冲电场主要沿环向向西;(2)脉冲电场在日侧的幅度普遍大于夜侧的幅度;(3)脉冲电场在日侧的持续时间普遍小于夜侧的持续时间.模拟结果中脉冲电场的特征与Zhang等人(2018)中基于范艾伦卫星数据的统计结果一致,从而验证了统计结果的可靠性.这些结果将有助于对辐射带高能粒子对极端空间天气的快速响应的理解.

As an interplanetary shock(IPS)compresses on the Earth's magnetosphere,it will launch impulsive electric fields in the inner magnetosphere,which may further induce prompt acceleration and injection of relativistic electrons.Thus,impulsive electric field could be important to the topic of dynamics in the inner magnetosphere.We perform a MHD simulation on magnetospheric response to interplanetary shock occurred in 2015 December 19th with the Space Weather Modeling Framework(SWMF),to investigate its characteristics on spatial distribution and temporal evolution.The result shows that:(1)impulsive electric field is induced mainly westward;(2)its amplitude in dayside is larger than it in nightside;(3)its rising time in dayside is shorter than it in nightside.The three main characteristics in simulation are consistent with the statistical results by Zhang et al.(2018)with Van Allen Probes measurements.These results will be helpful for the understanding the prompt response of high energy radiation belt particles to extreme space weather conditions.